Intravascular catheters, including peripherally inserted central catheters (PICC) and central venous catheters (CVC), have been used to provide therapy, administer pharmacological and/or nutritional agents, and meet other clinical needs such as hemodialysis, blood drawing, and so on. In general, it is recommended that the appropriate location of an intravascular catheter is the lower ⅓ of the superior vena cava (SVC) to the junction of the SVC and right atrium (RA), also known as the cavoatrial junction (CAJ) region, as shown in FIG. 1. However, due to a variety of factors, such as tortuous venous pathway, venous anomaly, and incorrect initial estimation, approximately 5-32% of all PICC line placements result in malposition. This malposition can result in both clinically and financially adverse outcomes, such as increased infection risk, thrombosis, cardiac tamponade and/or additional chests X-ray exposure. To prevent or reduce possible adverse outcomes, a PICC line should generally be located at the desired location in the lower ⅓ of the SVC to CAJ.
ECG-guided intravascular catheterization, such as PICC catheterization, has been used to reduce the chance of PICC/CAC line malposition by means of an electrocardiogram (ECG) sensor equipped stylet, which is a wire-like slender medical device, as illustrated in FIG. 2. ECGs have long been used for evaluating heart condition by recording and monitoring the electrical activities of the heart. The ECG can be used for various clinical applications. One example is the detection of abnormal electrical patterns and/or morphology of ill patients, aiding in the diagnosis of cardiovascular disease, and guiding therapeutic decisions. Another example is assisting clinicians to advance a PICC or CVC to the CAJ area.
During each heart beat cycle, the heart cells change the membrane potential, and repeat the “depolarization—reduction (less negative) of the electrical charge (membrane potential) toward zero” and “repolarization—returning of the membrane potential to a negative resting potential” process. During each cardiac cycle, a heart orderly progresses (or spreads) an electrical charge from the atrium, triggered by the pacemaker cells in the sinoatrial (SA) node, throughout the heart muscle through the conduction pathways in the heart. This progression of electrical wave is detected as tiny rises and falls in the voltage among electrodes placed around the heart.
A typical ECG wave of the cardiac cycle includes a P wave, a QRS complex, a T wave, and a U wave which is not always visible, as shown in FIG. 3. During atrial depolarization, an electrical charge spreads from the SA node to the right atrium, then the left atrium. This turns into the P wave. The QRS complex represents the rapid depolarization of the right and left ventricles. The T wave indicates the repolarization of the right and left ventricles.
The current prevailing ECG-guided catheterization method is to estimate the catheter tip location by monitoring the P wave amplitude change. However, this method has several limitations to accuracy and practicality when navigating through the venous system. One example is the abnormality of the P wave with arrhythmia or abnormal heart activity, which can render standard techniques inoperable. Due to these limitations, a conventional ECG-guided catheterization generally requires confirmation of the final catheter tip location with fluoroscopy and/or a post-operative chest X-ray which results in additional cost and X-ray exposure.
Accordingly, it would be desirable to provide an endovenous access and guidance system that overcomes the shortcomings of the prior art devices described above.